Wash before shooting primer ?

[Doug C]

I will be stripping my car of all paint today (and probably tomorrow too) WITH polycarb PADS on A GRINDER (no chemicals). The car sits outside under a car port. I planned to wash the entire surface with either deluted "Prep & Etch" (Phosporic acid) or Water/Vinegar (@ 4:1). Which do you guys recommend ? Or should I just clean with a wax & grease cleaner and shoot the primer?

If using one of the acid washs mentioned.. how will I final rinse with clean clear water while the windshields and all glass is removed but wiring harness and electricals are still there? (all interior has been removed though).

Doug C

[wcfvw69]

On raw metal, I always wipe it down with an oil and grease remover. I then make sure my first coat of primer is an "etching" primer that will "bite" into the metal for a good bond.

If I'm going to leave it in primer, I'll follow up the etching primer coat with an epoxy coat of primer that seals off any moisture getting to the metal.
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[Doug C]

thank Bill. Unfortunately I won't be able to get any etching primer. I do have Epoxy Primer though. I would think the polycarbide grinding pad would leave plenty of tooth for the epoxy primer though. If not, I could go over the bare metal with a red scotchbrite - which I was going to do anyway if I got any flash rust before spraying the epoxy primer. And/Or I could use the red scotchbrite in conjunction with whatever acid wash I ended up using.

The car will stat outside but the car port will become a temporary enclosed both before spraying the primer and the car will be painted with in a few days after that.

I'm leaning towards water/vinegar and a red scotchbrite. Either way - I'm afraid of getting it on electricals during the wash and rinse.

Doug C

[jspbtown]

I have always just used a degreaser/wax remover.

One thing I did start doing was to go over everything with alcohol after the degreaser and before the paint.

I don't know why but it reduced my contamination issues significantly.

[wcfvw69]

They make an acid prep wipe for bare metal as well. It provides an etching for the epoxy to stick to as well. That's all the etching primer is. It just has a light acid in it.
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[eshan2]

You have to be careful with etch primers. Some epoxy primers have bad reactions with them. It is best to follow the paint systems instructions. Some epoxy needs a specific grit sanding scratch left behind.
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[esde]

If you do not get some 2k primer sprayed on the epoxy within a few days you will have a ton of work ahead. There's only a few day window where the two will bond, after that the epox will need to be mechanically scuffed, and it eats through sanding discs. Ask how I know

[panicman]

I bought and used the wipes from the paint store.

The product degreases and removes any contaminants, and it dries immediately. I don't remember the active ingredients in it, but it is intense; it ate through my nitrile gloves pretty quickly.
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[Mike Fisher]

I would use the phosphoric acid on all bare metal, since you can not strip a whole car & primer it in 1 day. Buy the 2k primer & spray it over the epoxy primer the same day.
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[brainwash]

[jason]

It depends on the product your going to use on what to wipe with. I use SPI epoxy. It says it has the etching chemicals in it for bare metal. I talked to them and they say to clean with their cleaner and shoot the primer. You have a week to topcoat or to add filler on it. If longer scuff. They also say you don't have to topcoat. Not expensive either.

Epoxy usually doesn't like etching chemicals, you need to surgically clean. When the metal heats up the chemicals leach out and attack the primer.

[Doug C]

Mike wrote:

[Doug C]

[Mike Fisher]

The epoxy dries rock hard, so it's wise to spray some high build primer the same day & not wait 5 days for skim coat of filler. What if your 5 day skim coat filler doesn't stick to the Epoxy! Show us your Volvo & spray booth now!
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66 sunroof,67,70,71,71,71AT,72,72AT,73 Parts
two 57 oval ragtops sold
'68 Karmann Ghia sold

Society is like stew. If you don't keep it stirred up you end up with a lot of scum on the top! - Russ_Wolfe/Edward Abbey

[Doug C]

Here it is from a couple days ago, and before I covered the sides of the temporary booth with plastic sheet (just before it started raining too btw). The metal is even cleaner today after I re-abraided the surface w/150grit followed by a red scotchbrite pad (appx 350 grit). I wanted to avoid having to worry about removing any phosphoric acid - but I've decided to go ahead and wipe the car down with some.. because I noticed tiny stain spots on the surface that I could not remove with the 150 grit today. I'm afraid of them being rust.

Doug C

[Joseph DR]

[kman]

Nice Volvo. Even if it isn't a VW.

[Doug C]

[/quote]Doug, that's a cool lookin' car and fun project!
...
I would recommend the high build primer over skimming the whole car with filler.[/quote]

Thanks! I love this car but there are always a few old vw's I'm always keeping an eye out for. And the help on this forum for paint and body is amazing!! Thanks guys.

Yea, when Mike eluded to 'priming over the epoxy immediately' I totally spaced on the high build primer.. of course I am aware of doing that. I just (for whatever reason) do not immediately think of it as primer - I guess because it's often referred to as 'shaper/surfacer' I guess.

I actually do have a new 1 quart can of the Polyester high build Surfacer that I bought to spray over the worst areas (passenger rear quarter). But I am now seeing that I should have invested in an entire gallon to do the whole car as it now seems a better choice than the lite weight filler that I did buy.

Doug C

[kman]

For the yellow brown flash rust stains that show up, I use a red scuff pad sprayed (not soaked) with some metal ready. Wait a about 1/2 hour or so then clean as usual.

[Doug C]

ok, well.. what I ended up doing is : diluting my phosphoric acid 30% to water @ 70%. The product (a general hardware store phos acid) suggested a 50/50 mix with water to promote adhesion before painting bare metal and I'd read here of someone doing a 30/70 mix with good results. I was not after better adhesion but rather to dissolve microscopic rust before shooting my primer. I applied it like Eastwood's video of there "After Blast" phosphoric acid product for bare metal - that is, I sprayed it on and almost immediately wiped it off. The surface looked good when finished.

The bad: after reading on this forum of the need to rinse phosphoric acid after applying it, in order to neutralize it - I rinsed the hood and two front wings with clean water, dawn dish soap and a red scotchbrite. These areas started turning yellow/gold as I was doing this rinse !!! Crap! It's a mild rust flash all over these areas. So, I stop as soon as I realize this and start drying the front of the car. Lots of yellow/gold on my towel. Once I had it dry I scrubbed this whole front area with a dry red scotchbrite which removed it. Then I went over the entire car with grease & wax remover. The whole car looks good to go again for primer, as far as I know.

What do you guys reckon though? Is grease and wax removed enough to neutralize the 30/70 mix? My rags are pretty clean now btw. I guess I effectively removed all of the mix from the front of the car with the damn wash, but whatever.. there is not rust and no rain in the forcast for a couple of day. I'd like to shoot primer asap.

Doug C